S2K Commerce - Products Dropdown
S2K Commerce - Order Entry
OEM Mercury & Tohatsu Thermostat Gasket
Mercury & Tohatsu 4HP-30HP FourStroke Thermostat Cover Gasket
Genuine OEM thermostat cover gasket used on many Mercury and Tohatsu 4-stroke outboards ranging from 4HP through 30HP. This gasket helps create a proper seal between the thermostat housing and engine components during cooling system service.
Commonly replaced during thermostat maintenance, cooling system repairs, or preventative service on compatible Mercury, Mariner, Nissan, and Tohatsu outboards.
Compatible Mercury Applications
| Engine Range | Engine Type | Application Notes |
|---|---|---|
| 4HP / 5HP / 6HP | Mercury FourStroke | Select models and serial ranges |
| 8HP / 9.9HP | Mercury FourStroke | 209cc applications |
| 9.9HP ProKicker | Mercury FourStroke | Select ProKicker applications |
| 15HP / 20HP | Mercury Carbureted & EFI FourStroke | 2-cylinder applications |
| 25HP / 30HP | Mercury EFI FourStroke | 3-cylinder applications including Jet models |
| 15HP SeaPro | Mercury FourStroke | International SeaPro models |
Compatible Tohatsu Applications
| Engine Range | Engine Type | Application Notes |
|---|---|---|
| 8HP / 9.8HP | Tohatsu FourStroke | Select MFS models |
| 15HP / 20HP | Tohatsu FourStroke | Select EFI and carbureted models |
| 25HP / 30HP | Tohatsu FourStroke | Select EFI applications |
| Nissan Marine | FourStroke Outboards | Select rebadged Tohatsu applications |
OEM Part Numbers & Cross References
| Brand | Part Numbers |
|---|---|
| Mercury | 8M0214960, 853702, 853702005, 898101194 |
| Tohatsu | 3H6010320, 3H6010320M, 346010320, 346010320M, 350020320, 350020320M |
| Sierra | 18-60920 |
| Mallory | 9-60920 |
What This Thermostat Gasket is Used For
This OEM thermostat cover gasket is used to properly seal the thermostat housing during cooling system operation on compatible Mercury and Tohatsu outboards.
Replacing the gasket during thermostat service helps prevent coolant leaks, improper thermostat sealing, and cooling system pressure loss.
Thermostat gaskets are commonly replaced whenever the thermostat housing is removed for inspection, thermostat replacement, or routine maintenance.
Using the correct OEM gasket helps maintain proper fitment and sealing performance in harsh freshwater and saltwater marine environments.
Key Features and Benefits
- Genuine OEM Mercury and Tohatsu thermostat gasket
- Fits many 4HP-30HP FourStroke outboards
- Helps seal thermostat housing properly
- Supports cooling system reliability
- Common replacement during thermostat service
- Designed for marine cooling system environments
- OEM-quality fit and material construction
- Compatible with multiple Mercury and Tohatsu platforms
Thermostat Gasket Details
- Part Type: Thermostat Cover Gasket
- Primary OEM Number: 8M0214960
- Application: Mercury & Tohatsu FourStroke Outboards
- Horsepower Range: 4HP-30HP
- System: Engine Cooling System
- Use: Thermostat housing sealing
- Material: OEM marine gasket material
FAQ
What does this thermostat gasket fit?
This gasket fits many Mercury and Tohatsu-built 4-stroke outboards
ranging from 4HP through 30HP depending on model and serial range.
Should I replace the gasket when replacing the thermostat?
Yes. It is recommended to replace the thermostat gasket whenever the thermostat housing is removed to help ensure a proper seal.
Is this an OEM Mercury part?
Yes. This is a genuine OEM-style thermostat gasket cross-referenced to Mercury part number 8M0214960 and related superseded numbers.
Does this fit Tohatsu and Nissan outboards?
Yes. Many Mercury small FourStroke outboards are manufactured by Tohatsu, and this gasket also cross references to several Tohatsu and Nissan Marine part numbers.
Can a damaged thermostat gasket cause cooling issues?
Yes. A leaking or damaged gasket can contribute to improper thermostat operation, coolant leakage, or inconsistent engine temperatures.
Dealer Discounts & Store Policies
Dealer / Marine Industry Discounts
Are you a marine dealer, technician, boat builder, or industry professional? We offer dealer pricing for qualified marine businesses.
Shipping Policy
- Free shipping on orders over $100 (continental U.S.).
- Orders ship via UPS, USPS, and FedEx.
- Orders received before 5:30 PM EST ship the same business day.
- Typical delivery time is 1–5 business days.
30-Day Return Policy
- Returns accepted within 30 days of delivery.
- Items must be new, unused, and in original packaging.
- Return authorization is required before sending items back.
Need help with a return or order question?
Contact Us
Phone: 941-721-3000
Searchable Terms
8M0214960, 853702, 853702005, 898101194, 3H6010320, 3H6010320M, 346010320, 346010320M, 350020320, 350020320M, thermostat gasket, Mercury thermostat gasket, Tohatsu thermostat gasket, Mercury 25HP thermostat gasket, Mercury 30HP thermostat gasket, Tohatsu thermostat cover gasket, Nissan Marine thermostat gasket, Sierra 18-60920
3H6010320
3H6010320M
346010320
346010320M
350020320
350020320M
5040066
8M0214960
853702
853702005
898101194
HZX219300003
18-3632
19300-ZX2-003
5033721
5033721
6CB-12411-00-00
67F-12411-00-00
67F-12411-01-00
8M0175321
8M6010296
8556761
18-3628
18-3628-1
18-43175
19300-ZW9-003
19300-ZY3-023
3NV010300
3NV010300M
3R3010300
3R3010300M
3SA010300
3SA010300M
6G8-12411-00-00
6G8-12411-01-00
6G8-12411-02-00
6G8-12411-03-00
66M-12411-00-00
66M-12411-01-00
8M0119207
825212
825212A1
825212T02
825212001
855676
855676A1
855676002
855676003
855676005
25hp 2004 & Up
30hp 2004 & Up
40hp 2004 & Up
50hp 2004 & Up
75hp 2007 & Up
90hp 2007 & Up
100hp Pre 1997
Johnson / Evinrude
10hp aa Model, 2012 (aa, ab, af Model)
15hp aa Model, 2012 (aa, ab Model)
Mercury
8hp 1995-2024
9.9hp 1995-2000
13.5hp 1999-2006
15hp 1998-2021
25hp 1998-2006
30hp 1999-2021
40hp 1999-2006
50hp 1995-2001
75hp 2000-2003
90hp 2000-2003
Tohatsu
8hp 2004-2022
9.8hp 2003-2022
9.9hp 2002-2011
15hp 2002-2017
18hp 2002-2008
20hp 2008-2017
25hp 2002-2018
30hp 2002-2018
60hp 2014-2019
75hp 2014-2019
90hp 2014-2019
Yamaha
4hp 1986-1988, 2001-2023
6hp 2001-2022
8hp 2001-2024
9.9hp 1985-2024
15hp 1998-2024
20hp 2006-2024
25hp 1998-2018
30hp 2005-2024
40hp 2000-2024
50hp 1995-2024
60hp 2005-2024
70hp 2012-2023
75hp 2005-2024
80hp 1999-2000
90hp 2005-2024
115hp 2005-2024
130hp 2003, 2021
150hp 2003-2010
175hp 2003-2005
200hp 2003-2019
225hp 2003-2018
250hp 2003-2018
300hp 2004-2009
350hp 2008-2018
425hp 2018-2023
450hp 2023
HZW919300003
HZY3-19300-023
HZY319300023
13012
18-3541
18-3611
18-3628
18-3628-1
18-43175
19300-ZW9-003
19300-ZY3-023
3NV010300
3NV010300M
3R3010300
3R3010300M
3SA010300
3SA010300M
5041185
6AH-12411-00-00
6G8-12411-00-00
6G8-12411-01-00
6G8-12411-02-00
6G8-12411-03-00
66M-12411-00-00
66M-12411-01-00
8M0119207
825212
825212A1
825212T02
825212001
8252121A1
855676
855676A1
855676002
855676003
855676005
9-43036
369650210
369650210M
369650211
369650211M
47-161543
5040180
3A3021040M
353010320
353010320M
353021040
353021040M